A Water Shortage Solution: Reclaimed Wastewater

Recent fires in Southern California are a vivid reminder that half of the United States is experiencing some level of drought, and 15 percent of the country is currently dealing with extreme to exceptional drought—“a pattern that has been persistent for much of the past several years,” according to NASA. As a result, many communities and agricultural producers are looking for alternative systems, including reclaimed wastewater, to deliver clean drinking and irrigation water.

The need for water is so extreme in the Southwest that Wichita Falls, Texas is planning to be one of several communities in Texas to reuse wastewater directly for potable water use. In a direct potable reuse application, wastewater is piped directly from a treatment facility to a drinking water treatment and distribution system. Commonly referred to as “toilet-to-tap” it is a notion that sounds more out of the norm than it is in reality. In fact, many drinking water facilities draw from sources that are downstream from a wastewater effluent discharge. The dilution, UV exposure, and natural filtration that take place in nature are replicated in the systems at the Wichita Falls water treatment facility.

The Importance of Water Conservation

The need to conserve drinking water resources, even in less drought-prone areas, is still important. The EPA puts the global situation in perspective: “Water covers approximately 70 percent of the Earth’s surface, but less than 1 percent of that is available for human use.” Furthermore, water use is increasing, particularly in the U.S., despite the increased use of conservation measures. This puts a strain on water resources, even in places without frequent drought conditions, like the water-rich Northeast.

For example, the University of Connecticut found itself in a situation where water studies showed that over time, campus water demand would exceed local supply. In addition, during a drought period in 2005, a portion of the Fenton River ran dry. There was some debate regarding if withdrawals from the University-owned Fenton wellfield during the University’s seasonal peak demand was a contributing factor. The University decided that rather than debate their contribution, they would proactively improve the water balance in the region.

To address this challenge, the University implemented conservation measures, streamflow monitoring, and withdrawal management protocols; however, UConn also sought a reliable alternative strategy to meet its current and future water needs. The solution was to design a sustainable reclaimed water facility (RWF) that would reduce its need to draw on local sources, provide for increased future demand, and preserve natural resources. The University uses the reclaimed water for non-potable uses in its cooling tower, chilled water system, and (with some additional treatment) high-pressure boilers. Woodard & Curran operates the facility, which can process up to 1 million gallons of wastewater per day. During peak seasons, the University expects to reduce its potable water demand by up to 40%.

The Scale of Discharge and Potential Reuse

From a sustainability point of view, while it requires energy and expense to treat wastewater effluent for potable and non-potable uses, the amount of treated wastewater is enormous. A water reuse study from the National Research Council noted that 32 billion gallons of treated wastewater effluent is discharged to U.S. waters per day. Reuse facilities have the potential to make a significant difference. The water reuse facility in Wichita Falls itself would be able to recycle 5 million gallons per day. Water Conserv II in Winter Garden, Florida—one of the world’s largest reclamation projects, which is operated in part by Woodard & Curran—delivers 50 million gallons of water per day for irrigation purposes and aquifer recharge via rapid infiltration basins.

UConn’s RWF is an example of direct non-potable reuse, and Water Conserv II exemplifies a combination of direct and indirect use. The latter can be equally important. Aquifer replenishment is a key component of many current reclamation projects. At one system in Orange County, California, operated jointly by the water and sanitation districts, roughly half of the 70 million gallons of water per day produced at the reclamation facility is directed via a 13-mile pipe to recharge basins that filter the water through sand and gravel to replenish groundwater aquifers. The remaining 35 million gallons are pumped into injection wells to serve as a seawater intrusion barrier.

The Regulatory Framework

As one would imagine, states and the EPA are responsible for regulating water reuse; however, these entities are currently revising (or need to revise) their policies and regulations to ensure that beneficial reuse systems can operate sustainably and efficiently. The technology is not new, but states are just beginning to look at regulating the early adopters. As operators of the first reuse facility in Connecticut, one of the largest reuse facilities in the country, and designers of the first in Massachusetts, we understand the challenges that lie ahead.

One question that often arises is how much treatment is required for the reused water’s intended use. Bloomberg news reported (in an extensive and informative piece on water reuse) that one reuse facility in Virginia is required by law to treat its wastewater beyond drinking water standards, yet the reused water is not used for consumption. Rather, the water is used to cool data centers.

Public Perception and Education

Government may not be the greatest obstacle to the expansion of reused wastewater. It will likely be public perception. News stories about the potential for direct reuse in Wichita Falls focused on the negative reaction many residents expressed for the project. Despite an information campaign to educate the public, residents voiced concern about the ability to remove contaminants completely. The truth is that there will be challenges in dealing with microconstituents (such as pharmaceuticals) in the waste stream, but studies have shown that there is very low health risk. Reverse osmosis and microfiltration systems that remove most if not all of the microconstituents would be in use at these facilities.

The future of water use in this country and abroad will include some substantial form of reuse, particularly if climate change brings more drought and extreme temperatures. It will be essential for early adopters and operators to work with regulators to ensure that reasonable standards are consistently met. These parties should also do their part to help educate the public about the necessity and safety of reusing wastewater.